Truth: Acharya calls this “a hair-brained myth.” Colds are caused by more than 200 different viruses. You get the virus through inhaling infected air droplets sneezed or coughed by an infected person or by touching something that an infected person has touched and then transferring the germs to your mouth or nose. A wet head has nothing to do with it. This tale probably got repeated because virus-caused colds are circulated more in winter when people are more cooped up and in closer contact. Wet hair might have seemed a likely culprit.

Myth: The flu vaccine causes the flu.

Truth: The injected influenza vaccine is made from a killed virus so you cannot get the flu from it. Although vaccine side effects can include redness or soreness at the injection site, mild body aches and a slight fever, this is not the flu and symptoms should disappear within 24 hours. It can take a couple of weeks for the vaccine's protection to kick in, so if you're exposed to someone with the virus within a couple of days of your vaccination, it's not the shot that made you sick, but your sick friend. The only people who need to avoid the flu vaccine are people with allergies to eggs since eggs are used to make the vaccine. “This is one myth that potentially can cause harm (if believed),” Heng says. “We can prevent the flu, but because this myth is perpetuated, many people don't get vaccinated. Then they get the flu, others are exposed and epidemics can happen as a result.”

Myth: It takes seven years for swallowed chewing gum to pass through your digestive system.

Truth: Although gum is not digestible, it passes in a mass and won't stick to your insides, as some people believe. And while you're at it, go ahead and have a big slice of watermelon. You no longer have to worry about growing a watermelon in your belly if a couple of seeds slip down your throat.

Myth: You lose most of your body heat through your head.

Truth: Typically, we don't lose more than 10 percent of our body heat through our heads. Any uncovered part of the body will lose some heat, which is why wearing a hat is important when it's cold outdoors. It's not that the head loses more heat or loses it more quickly than other parts of the body. It's simply that the head is often the only part of the body not covered in the cold, says Dr. Richard Santore, an orthopedic surgeon and chief of staff at Sharp Memorial Hospital.

Myth: Reading in dim light or sitting too close to the TV will harm your eyesight.

Truth: “Although reading in poor light may cause eyestrain, it won't change your vision or increase your need for prescription eyeglasses,” Heng says. Your eyes are made up of muscles. Like other muscles in the body, if overworked, they get tired, but it won't permanently affect them. The only light that can damage your eyes is looking directly at sunlight or laser light.